I need help with this problem a/3 + 5a/12 = 9/4

Why is it so easy to buy on impulse and overspend with a credit card? what could you do to counteract this tendency?

Me d is also an option but i couldn't get it in the picture

Abarge can safely haul no more than 400 tons across the river. the barge has an empty weight of 24 tons. the average weight of the railroad cars is 4 tons each.bhow many railroad cars can the barge haul?